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retroPy's glitchi

🖋️ RetroPy MonoSprite Module Documentation (MicroPython)

The MonoSprite module defines a compact 1-bit-per-pixel sprite system optimized for memory efficiency. Used in RetroPy when color is not needed (e.g., fonts, effects), this format is loaded from .rsm files.

📦 Class: MonoSprite

🔧 Constructor

MonoSprite(source)
  • source: A .rsm file path, bytes, or file-like object.
  • Loads 1-bit frame data into memory and sets initial parameters.

🖼️ Frame Rendering

sprite.draw(color)

Renders the current frame at the sprite’s position using the specified palette index.

  • color: Palette index (0–255) to use for all “on” pixels in the frame.

🔍 Attributes

Attribute Type Description
x, y float Sprite position in world coordinates
position tuple (x, y) tuple for position
width int Frame width in pixels
height int Frame height in pixels
frame int Currently displayed frame
num_frames int Number of frames in the .rsm file
flip_mode int Bitwise: 0=none, 1=horizontal, 2=vertical

📄 String Representation

print(sprite)
# Output: MonoSprite(WxH x frames)

📂 RSM File Format (Custom)

  • Byte 0: Magic 'm'
  • Byte 1: Reserved
  • Bytes 2–3: Width (little-endian)
  • Bytes 4–5: Height (little-endian)
  • Byte 6: Frame count
  • Bytes 16+: Frame bitmap data (1 bit per pixel, row-aligned)

📌 Notes

  • The pixel data is tightly packed and unpacked at render time.
  • Uses world_to_screen() to support camera-relative drawing.
  • Suitable for fonts, UI elements, and overlay effects where color is uniform.
  • The .draw(color) method must be called with a palette index.